Objective        To construct the lentiviral vector of human smoothened (SMO) gene which can down-regulate the SMO expression in human periodontal ligament stem cells (PDLSCs).       Methods        According to the human SMO gene

3 sequences were designed to build RNA interference lentiviral vector. All the 3 vectors were packaged

in 293FT cells

and then transfected into the 293A cells. The interference efficiency was evaluated by quantitative PCR

and the optimal one were transfected into the PDLSCs. Western blotting were used to detect the interference effect of SMO gene and the effect on differentiation in PDLSCs. CCK-8 assay was used to test the effect of recombinant lentivirus on the proliferation of PDLSCs.       Results        Three SMO lentiviral RNAi vectors were constructed successfully and the lentiviral vector 1 was considered as the optimal one by quantitative PCR. The mRNA level of SMO was reduced by (28.5±2.5)% by this vector. The protein expression of SMO was decreased by 80% in the PDLSCs after transfected by the lentivector vector 1 when compared with the cells without transfection. This transfection also resulted in a decreased cell proliferation (1.090 9±0.199 2 vs 1.863 0±0.206 2

P

0.01) and a decreased expression of bone differentiation marker

RUNX2.       Conclusion       A lentiviral vector of SMO is successfully constructed

and SMO interference suppresses the proliferation in PDLSCs

and inhibits the differentiation of PDLSC to osteoblasts.